Tape drive window regulators for controlling the motion of a windowpane were developed for automotive applications in the 1970s as a low-cost alternative to conventional window regulators. Typically a tape drive window regulator has a drive member such as a hand crank or a motor attached to an inner panel of a motor vehicle door, a housing for the drive member, and a flexible plastic tape connecting the drive member to the windowpane, with the tape being guided by a rail. A drive drum is directly connected to the drive member, and has circumferentially spaced teeth. The tape has slots which receive teeth of the drive drum. The drive member rotates the drive drum which, in turn, moves the tape to pull or push the windowpane up and down between a full up position and a full down position in a door.
While these designs work well, a problem has existed in connection with using a tape drive window regulator assembly for alternative manual and electric designs. Many motor vehicles are produced and sold with the option of either a manual regulator or a "power" option. Unfortunately, however, manually driven systems and motor driven systems have requirements and specifications which differ from each other. A manually driven window regulator normally includes a hand crank connected to the regulator by a spindle, clutch cup and spring. Automobile makers (sometimes referred to as Original Equipment Manufacturers or OEMs) require a hand crank to completely raise the windowpane from the full down position to the full up position in no more than a certain number of revolutions, typically about 4.5 revolutions. OEMs also restrict the amount of effort required of an operator to operate the hand crank. As the force to operate a manual window regulator is in part a function of the size of the drive drum, this restricts the maximum permissible size of the manual drive drum. For electric motor driven window regulators, in contrast, OEM requirements are directed toward a limitation of the time it takes to raise a windowpane to the full up position from the full down position. This restriction limits the size of the electric drive drum to a range which unfortunately may not overlap the size range for drive drums on manual window regulators. Consequently, two different tape drive regulator designs have been needed for the same vehicle, one for electric, and one for manual. With the ever-present pressure to reduce costs, it would be desirable to commonize the parts of a tape drive window regulator to the greatest extent possible, while still satisfying the OEM's competing design requirements for manual and electric design variations.
In view of the foregoing, it is an object of the present invention to provide a window regulator with reduced cost, complexity and enhanced manufacturability. It is yet another related object of the present invention to provide a tape drive window regulator having a design which readily accommodates alternative manual drive and electric drive assemblies meeting their respective OEM requirements. It is an additional object of the present invention to provide a window regulator that is highly reliable in operation.